Aspects of the invention relate to an elastic joint, in particular for a wheel suspension of a motor vehicle, and may relate in particular to a rear wheel suspension of the vehicle.
In the modern motor vehicle technology it is known, in particular for the rear wheel suspension of a passenger car as well as for a motor lorry, to realize so called elastic mountings or elastic joints, the principal structure of which is formed by a rigid inner armature, in particular made of metal, like a rigid sleeve or a support rod, an outer armature like an outer sleeve, and an elastomeric body disposed between the armatures. The elastomeric body serves to separate, in particular acoustically insulate, the vehicle body from the vibration loaded wheels. Also the high occurring dynamic vehicle loads are to be born in the elastic joints. There is a large number of designs of elastic joints, the elastomeric bodies of which are usually formed by a purely elastic material, wherein hydraulic functional components may also be added.
Aspects of this disclosure are directed in particular towards the elastic joints having a spring body of merely elastomeric material between the rigid armatures.
From EP 1 505 311 A1 a bearing bush is known for a motor vehicle, the bearing bush having a sleeve-shaped, rigid inner armature as well as a sleeve-shaped outer sleeve of weaker form, between which an elastomeric body is injection molded. The outer sleeve is provided with a restriction for the adjustment of the spring characteristic of the elastomeric body, whereby two elastomeric sections are formed, the deformations of which influence each other respectively. In order to reduce the stiffness of the bearing bush in one radial direction so that the bearing bush is soft in one radial direction and stiffer in the other, a recess is realized in the elastomeric body along part of the circumference.
An elastically resilient pivot joint for the mutually pivoting connection of a wheel trunk with a guide member is known from DE 32 05 716 C2. The elastomeric body vulcanized between the armatures can be partitioned into two circular sections with different strength in the radial direction by means of a central bulge. An embodiment of an elastic joint, similar thereto, is known from KR 2009 009 8978, in which the partition by sections of the elastomeric body is realized by a restriction in the outer armature.
It became apparent in the known elastic joints, in particular for motor vehicles, that the ratio of axial stiffness versus radial stiffness, which is an important characteristic for automotive engineers, cannot be realized to be sufficiently high. Ratios of little above 1.0 are common. For automotive engineers it is of particular interest to have a high stiffness ratio, wherein a cardanic stiffness remains as low as possible.
In order to structurally optimize these characteristics, the cost effect and the weight/usage ratio is of course not to be neglected but in particular should also be optimized.
A need therefore exists for an elastic joint, in particular for a wheel suspension of a motor vehicle, in which the ratio of axial stiffness over radial stiffness is high for a low cardanic stiffness while using cost effective and light materials.